Overview
Friction is a key biomechanical concept in sports and exercise, influencing how athletes initiate, terminate, change direction, and maintain control during movement. It is the force that resists motion when two surfaces are in contact with each other. In sports, friction can work to an athlete’s advantage by providing grip and stability, or it can hinder performance if it is excessive or poorly managed.
There are two main types of friction relevant to sport: static friction and dynamic (or kinetic) friction.
Static friction acts between two surfaces that are not moving relative to each other. It must be overcome to initiate movement. For example, when a sprinter pushes off the starting blocks, static friction between their feet and the surface provides the grip needed to generate forward force.
Dynamic friction occurs when two surfaces slide over each other. This type of friction resists motion once movement has begun. In some cases, reducing dynamic friction improves performance—for instance, using smooth swimwear to reduce resistance in water, or waxing skis to glide more efficiently over snow.
The amount of friction depends on two key factors:
The nature of the surfaces in contact (e.g. rubber vs. grass, skin vs. synthetic track)
The force pressing the surfaces together (e.g. body weight, downward pressure)
In many sports, optimising friction is essential. Athletes rely on high friction for grip and traction—football boots with studs, court shoes with textured soles, and chalk on hands in gymnastics or climbing all increase friction to enhance control. In contrast, sports like ice skating or luge are designed to minimise friction, thereby maximising speed and fluidity.
Friction also plays a critical role in safety and injury prevention. Surfaces with too little friction increase the risk of slipping, while excessive friction can cause abrasions or hinder movement. The right balance is crucial for both performance and protection. For example, artificial turf may increase friction compared to natural grass, potentially leading to higher joint stress or different injury patterns.
In sports equipment design, friction is carefully managed to improve performance. From the tread on tyres in cycling to the seams on a cricket ball, understanding how friction behaves allows athletes and engineers to manipulate conditions for maximum advantage.
Ultimately, friction is an invisible but powerful force that affects every movement in sport. Whether it's providing grip during a sprint start, enabling sharp changes of direction in court sports, or reducing drag in water or air, controlling friction is essential for efficient, safe, and high-quality performance.
